1. First-row d-block elements
Use sections 8 and 9 in your IB data booklet to compare the trend and the extent of the trend for atomic radius, first ionization energy and electronegativity between the 8 elements in period 3 and the 10 elements in the first row in the d-block.
What characteristic properties do the first row d-block elements have?
Compare and contrast their properties with potassium and calcium.
What are iron, nickel, manganese used for? Use an interactive periodic table.

2. First-row d-block elements
Variable oxidation states e.g. Fe2+ and Fe3+, Cu+ and Cu2+.
Form complex ions e.g. [Cu(NH3)4]2+
Form coloured compounds
Can act as catalysts
Show magnetic properties
Why?

3. Electron configuration

4. Common oxidation statesSc Ti V CR Mn Fe Co Ni Cu +1 +2 +3 +4 +5 +6 +7

5. Successive ionization energies
Compare the successive ionization energies of aluminium and vanadium
I.E. kJ mol -1 Al V 1
+578
+651 2
+1820
+1370 3
+2740
+2870 4
+11600
+4600 5
+14800
+6280

6. Transition metals/elements definition
A transition element is a d-block element that has an atom with a partially filled d-sub-level or that forms at least one stable cation that has a partially filled d-sub-level. (IUPAC definition) As a result according to the above definition zinc is not considered a transition metal.

7. Complex ions

8. which can be shared with incomplete d-subshell of TM
TRANSITION METAL COMPLEXES
= central METAL ION (or atom) with
a FIXED number of MOLECULES or ANIONS
(called LIGANDS)
bonded to it by DATIVE (COORDINATE) bonds.
“COMPLEX”
 have no net charge
eg Ni(CO)4
“COMPLEX ION”
 have a net charge
eg [CuCl4] 2-
= anionic (-ve) complex
[Ni(H2O)6] 2+
= cationic (+ve) complex
Ligands have LONE PAIR(S)
which can be shared with incomplete d-subshell of TM
to form the coordinate bond(s), and hence the complex
eg [CuCl4] 2-
ligand is :Cl-
[Ni(H2O)6] 2+
ligand is H2O:

9. Complex ions
Transition metals can form complex ions because their ions have a high charge density:
they have quite a large nuclear charge but are relatively small;
the 3d electrons are not so effective (as 2s or 2p electrons) at shielding the effect of the ionic charge which really comes from the nucleus.
This allows the transition metal ions to have a great polarising power and they can attract lone pairs from other atoms to form complexes.

10. Complex ions Complex ions are formed by: Example: [Fe(H2O)6]3+
a metal ion to which a number of ligands (molecules and/or negative ions) are bonded using a dative bond
Ligand = molecule or negative ion with a non-bonding pair of electrons which is used to make a dative bond
Example: [Fe(H2O)6]3+
Coordination number is the number of ligands that surround the metal ion.

11. Naming complex ions examples of ligands number H2O - aqua 1 - mono
OH hydroxo
2 - di
NH ammine
3 - tri
Cl chloro
4 - tetra
Br bromo
5 - pent
CN cyano
6 – hex
You name the number and then the ligand before naming the metal e.g. hexaaquairon (III) ion.
You use the name of the metal if the ion is positive but use –ate ending if negative e.g. ferrate, cuprate, vanadate.

12. More examples complex ions
[Fe(CN)6]3-
[Fe(H2O)6]3+
[CuCl4]2-
[Cu(NH3)4]2+
[Ag(NH3)2]+
Charge on the ion is the sum of the charges of the metal ion and the ligand.
Work out the charge of each metal ion in each of the complexes above.

13. Shapes of complex ions Depends on coordination number
If then shape = octahedral
If then shape = tetrahedral
(or square planar = less common)
If then shape = linear

14. Shapes of complex ions

15. Complex ions: types of ligands monodentate polydentate
1,2-ethanediamine

16. Polydentate ligands How many ligands? Ethanedioate, bidentate
EDTA; each molecule can form 6 dative bonds
Ethanedioate, bidentate

17. EDTA as part of a complex

18. [Fe(H2O)6] metal ion = Fe2+ [Fe(H2O)5OH] metal ion = Fe3+
Determine the charge on each complex ion – where the charge of the ion is not mentioned also determine that
[Fe(H2O)6] metal ion = Fe2+
[Fe(H2O)5OH] metal ion = Fe3+
[CuCl4] metal ion = Cu2+
[Mn(H2O)6] SO4
[Co(NH3)6] (NO3)3
[NH4]2 [Fe(H2O)6] (SO4)2
NaCoCl4 Co = 3+
K4Fe(CN)6

19. answers 2+ 2-
ion and Mn = 2+
both 3+
both 2+ 1- 4+

20. Coloured compounds

21. Coloured complexes

22. Colour wheel

23. Splitting d-sublevel in Cu2+ (octahedral ion)

24. Coloured compounds
What factors will affect the colour (or difference in energy, ∆E, between the 2 sets of d orbitals in a split d-sublevel) of a transition metal compound?

25. oxidation state of metal ion (the greater the oxidation state, the lower the distance between the ligand and metal)
nature of ligand (different repulsion/greater split e.g. by less electronegative atoms or ligands with greater charge density )(see spectrochemical series)
identity of metal ion/nuclear charge (attraction between nucleus and non-bonding pairs)
coordination number/number of ligands
shape of the complex ion

26. Coloured ions: factors affecting colour

27. Colour complex ions: examples

28. Challenge
Study the graphs on the next slide and use them together with the colour wheel in your textbook to identify the colour shown by each complex ion.
Use the information below about each ligand to identify which graph shows the absorption of ligand A and B. Justify your answer:
Ligand A: more electronegative; holds electrons more closely to nucleus
Ligand B: less electronegative

29. Nature of ligand

30. Spectrochemical series
See data booklet
The further up the series, the greater the difference in energy between the 2 sets of d orbitals.
The Cr3+ ion forms an octahedral complex with 2 neutral ligands X and Y. The colour of CrX63+ is blue while that of CrY63+ is yellow. Which ligand is higher up the series?

31. Magnetic properties
All substances can be divided up according to the effect they experience and show when placed in an external magnetic field.

32. Diamagnetic particles
Weakly repelled by external magnet
Have paired d-electrons and therefore create a magnetic field opposed or not aligned to an external field.
The paired electrons cancel out each other’s magnetic field so there is no net magnetic moment in the atom or ion.
Examples of diamagnetic materials in the first row d-block elements: Zn and Zn2+.

33. Paramagnetic particles
Attracted weakly to a magnetic field.
Atoms or ions that contain unpaired d electrons behave like small magnets. Because of their spin electrons create a magnetic field that can align itself to an external electric or magnetic field when exposed to it; unpaired electrons can do this because they can spin in any direction – they create a net magnetic moment.

34. Paramagnetic particles
The greater the number of unpaired electrons the more paramagnetic the material. The alignment is only temporary so they are only magnetic for a short period of time.
Examples of paramagnetic materials in the first row d-block:
atoms: all apart from Zn.
ions e.g. in compounds and complexes: e.g. Mg2+ has 5 unpaired electrons, Co2+ (3 unpaired electrons), Ni2+ (2 unpaired electrons), Fe2+ ( unpaired electrons).

35. Ferromagnetic
Ferromagnetic materials have unpaired electrons but can be made to order over a large range and by doing so produce a permanent magnet
Examples of ferromagnetic materials are iron, cobalt and nickel.

36. Transition metals catalysts
Catalysts lower activation energies allowing a chemical reaction to go faster. Catalysts are not used up.
Heterogenous catalyst: different phase as reactants.
Homogenous catalyst: same phase.

37. Transition metals as catalysts
Transition metals are good catalysts because:
they have the availability of 3d and 4s electrons and similar successive ionization energies which allow them to change easily between different oxidation states (homogenous catalysis)
have empty orbitals which can be used to make temporary bonds (heterogenous catalysts).

38. Heterogenous catalysis
Nickel in the conversion of alkenes into alkanes.
C2H4 (g) + H2 (g)  C2H6 (g)
Iron (atoms) in the Haber process
N2 (g) H2 (g)  2NH3 (g)
Manganese dioxide in the decomposition of hydrogen peroxide.
2H2O2 (aq)  O2 (g) H2O (l)
Palladium and platinum in a catalytic converter.
Cobalt in manufacture of vitamin B12
Iron ions, Fe2+, in the heme group which sits in the hemoglobin protein; it is a site which allows oxygen to be bonded more easily onto the hemoglobin molecule.

39. Heme group

40. Homogenous catalysis example
Overall: S2O82- (aq) + 2I- (aq)  2SO42- (aq) + I2 (s) Using catalyst Fe3+ 2Fe 3+ (aq) + 2I- (aq)  2Fe2+ (aq) + I2(s) 2Fe 2+(aq) + S2O8 2- (aq)  2Fe3+(aq) + 2SO42- (aq) Draw energy level diagrams to show the effect of using a homogenous catalyst. Homogenous catalysts provide a different reaction mechanism that lowers the activation energy.

41. VARIABLE OXIDATION STATES OF IRON
REDUCTION
Brown
Fe3+
Fe2+
Pale green
OXIDATION
Reduction carried using excess granulated Zn
in dilute sulphuric acid
2Fe Zn  2Fe Zn2+
Excess zinc can be filtered off after reduction.
Oxidation can be carried out using excess H2O2(aq)
in dilute NaOH solution
2Fe H2O2  2Fe OH-
Iron(III) will form Fe(OH)3(s) in alkali
Converted to Fe3+(aq) by adding dil. acid
Fe(OH)3(s) + 3H+(aq)  Fe3+(aq) + 3H2O(l)

42. OXIDATION STATES OF CHROMIUM+6 +3 +2
CrO42-
Cr2O72-
= chromate(VI)
= dichromate(VI)
YELLOW
ORANGE
[Cr(OH)6]3-
[Cr(H2O)5(OH)]2+
[Cr(H2O)6]3+
= hexahydroxo-
chromium(III) ion
= pentaaquohydoxo-
chromium(III) ion
= hexaaquo-
chromium(III) ion
DARK GREEN
GREEN
RUBY
[Cr(H2O)6]2+
Exist in equilibrium in aqueous solution.
GREEN predominates.
Ruby in crystal or
at very low pH.
= hexaaquo-
chromium(II) ion
BLUE

43. OXIDATION STATES OF COBALT
+ Excess
NH3 +2 +3
[Co(H2O)6]2+(aq)
[Co(NH3)6]2+(aq)
PINK / RED
STRAW YELLOW
UNSTABLE!
OXIDATION
by heat with H2O2 in NaOH(aq)
OXIDATION
Quickly by H2O2 in NH3(aq) or slowly by O2 from air
Co(OH)3(s)
[Co(NH3)6]3+(aq)
DARK BROWN
DARK RED
STABLE

44. OXIDATION STATES OF COPPER+2 +1
[Cu(H2O)6]2+
[Cu(H2O)6] Cu
BLUE
BLUE
REDUCTION
by heating with copper in conc. HCl
DISPROPO RTIONATION
by adding dil. H2SO4
[CuCl2]-
CuCl(s)
COLOURLESS
WHITE
PRECIPITATION
by adding water
Note: Copper(I) oxide, Cu2O is the brick-red ppt. formed during a positive Fehling’s test.
CuCl(s)
WHITE

45. Match up correct explanation
Typical property
Match up correct explanation
A. Form coloured compounds
1. Variable oxidation states and empty orbitals
B. Can acts as a catalyst
2. Transition metal ions have high charge density
C. Variable oxidation states
3. Partially filled split 3d sublevel and d-to-d transitions
D. Can form complexes or complex ions with negative ions and molecules
4. 3d sublevel to be filled closer to nucleus than 4s sublevel. Increased shielding offsets increased nuclear charge. Similar atomic radii
E. Magnetic properties
5. Small differences in successive ionization energies in 4s and 3d
F. Similar first ionization energies
6. Unpaired 3d electrons